This invention relates to firearms, and in particular to a recoil mechanism for an auto-loading firearm having a gas-operated action bar assembly.
Gas-operated firearms usually including a receiver and a breach-bolt mechanism mounted for reciprocal movement to and from a battery position in the receiver. The bolt is linked to a piston or a piston and cylinder assembly which is automatically operated by a portion of pressurized gas which is developed upon the discharge of a round or cartridge, and bled from the gun barrel to the cylinder.
The pressurized gas that is bled from the barrel is converted to mechanical energy through the movement of the piston that is utilized to mechanically unlock the bolt mechanism after firing the firearm. It withdraws the bolt mechanism from the battery position, ejects the spent shell, and advances a fresh shell into position for loading into the breach chamber.
Simultaneously, an action spring (also known as a breach block return spring or buffer spring) coupled to the bolt mechanism is compressed. Subsequently, the action spring returns the bolt mechanism to the battery position, loading the fresh shell into the breach chamber. The mechanism including the action spring is commonly referred to as the “recoil mechanism” of the gun, for it recoils the bolt back into the firing position.
Typically the recoil mechanism is located in the butt stock of the firearm. On occasion, the recoil mechanism is located in the receiver, itself. Wherever located, the recoil mechanism is typically fixed in configuration, no matter what size round may be fired by the firearm.
U.S. Pat. Nos. 689,283; 659,507 and 730,870 are examples of typical auto-loading firearms in the form of a shotgun. In these patents, the recoil mechanism is located in the butt stock. The concepts of the firearms of these patents have been used for over 100 years, and are still commonly employed.
In prior art recoil mechanisms in the butt stock, the recoil mechanism slopes at an angle of 15° or more. When a cartridge is fired, the kinetic energy of the blast is directed rearwardly, actuating the breach block assembly. The inertia of the breach block assembly is forced into the angled recoil mechanism where it compresses the spring of the recoil mechanism. It is this motion and energy transfer that causes the barrel of the gun to be elevated at an angle much more pronounced than would be seen if the recoil was in essentially a straight line parallel to the barrel.